CITYPEOPLE

CITYPEOPLE; Mapping the Perfect Detour

By ADAM FIFIELD

Published: May 6, 2001

WITH the urgency of a football coach scrawling plays on a blackboard, Mark Zannoni pins a diagram of subway tracks to his bulletin board, draws vigorous arrows and loops, and describes a series of tricky-sounding maneuvers.

''You can wrong-rail,'' he begins briskly, ''which is sending a train in the opposite direction of normal traffic. Then there's single-tracking, where you use a single piece of track for traffic in both directions. You can also split a line by terminating it in the middle of a route and creating a northern part and a southern part.

''And, in rare instances, you have to do a baton move. Here, a motor instructor standing on the platform will hand the train operator a metal baton, and that baton is the authority to be on that part of the railroad. When you have that baton, only you can be on that piece of track.''

These moves, as Mr. Zannoni calls them, are used to shift trains temporarily to alternative routes when segments of track are taken out of service, usually for repair or improvement work. In the last two years, the volume of work has increased, meaning more diversions. Other less frequent rerouting culprits include emergencies, flooding and police investigations.

The most seasoned, and most prolific, of New York City Transit's six subway service diversion planners, Mr. Zannoni has drawn up more than 500 blueprints for subway detours in those two years. One map outlines the complex weekend rerouting of the A and F lines, a plan Mr. Zannoni helped devise, due to the rebuilding of a track switch near the Jay Street station in Brooklyn.

Some changes are simple, others circuitous. Coming up with alternative routes in a labyrinthine system of 656 miles of track requires an appetite for solving puzzles.

A cartographer with a master's degree in urban planning from Columbia University and an uncapped curiosity, the intense Mr. Zannoni revels in the challenge. For him and his colleagues in the transit agency's Operations Planning Division, a subway map is not a fixed set of intersecting lines, but a sprawling organic landscape pulsing with possibilities and predicaments. Mr. Zannoni, 31, says he was drawn to New York City from his native city, Cleveland, in part by the ''vastness and beauty of her subway system.''

Since New York's system, unlike most, operates 24 hours a day, seven days a week, the need for precise coordination between planners and those performing maintenance and construction work is acute.

''The general rule,'' he said, ''is that you never want to hit a passenger twice on the same trip.''

Last fall, Mr. Zannoni's job changed from plan writing to what is called look-ahead, in which he determines the schedule of future service changes for all IRT trains. He weighs the urgency of a request against its potential impact on passengers and other requests.

''There are a lot of things to look out for,'' he said. ''I received plenty of requests for the weekend of June 10, for example, but that happens to be the Puerto Rican Day Parade, so there can be no impacts anywhere in Midtown.''

When Mr. Zannoni leaves his office, another job awaits him at home.

In his cramped Chinatown apartment on a cluttered L-shaped desk wedged snugly between his bed and the wall are a computer, a scanner, a phone, a fax machine and two printers. Affixed to the wall is an enormous bulletin board plastered with several layers of maps, calendars and personal reminders. This comprises the headquarters of the Cleveland Map Company, a business begun by Mr. Zannoni in 1995 that produces and publishes uniquely detailed tourist and specialized maps.

Mr. Zannoni's first map, of Cleveland, is now in its third edition. It has sold more than 32,000 copies. The company's other products constitute a sundry array. A map of the transportation infrastructure of Mozambique (Mr. Zannoni studied in nearby Zimbabwe during college and has always had a special interest in Mozambique), replete with in-depth descriptions of development corridors and flight patterns of airlines, has been bought by the United Nations and Harvard University.

He also made a campus map for Case Western Reserve University and a series of maps of Adícora, Venezuela, included in a book his company published on windsurfing in the region. Future products may include an alternative New York subway map to the one his agency produces -- ''though never while I remain in the service of the Transit Authority,'' he said -- and other specialized New York maps.

The maps are created on his computer, printed at a Manhattan printer, and sold at stores throughout the country and on the Web at www.clevelandmap.com.

Mr. Zannoni's diversion designs are usually plotted out months ahead of time, but last summer the planner found himself faced with the task of drawing one up in a matter of hours.

About 11 p.m., as he waited at the West Fourth Street station after dinner with a friend, an announcement crackled over the public address system that his train, the D, was delayed. A conductor informed him that a train had derailed at the DeKalb Avenue station in Brooklyn.

Mr. Zannoni took the F to the transit agency's command center in Downtown Brooklyn, where he spent the next six hours figuring out how to get trains around the obstruction. Fortunately, the track was cleared about 6 a.m., minutes before the morning rush began.

''I came home,'' he says, ''passed out till about 10, then went to work.''

Photos: For Mark Zannoni, who plans alternative routes for the subways, a subway map is an organic landscape of possibilities and problems. Below is his depiction of the rerouting of the A and F. (Steve Hart for The New York Times)

Adam Fifield is the author of the memoir ''A Blessing Over Ashes: The Remarkable Odyssey of My Unlikely Brother'' (Morrow).